Robert Rappaport wrote:
[snip]
.... This is because the vfs running on the same node where the
samba server is running is not necessarily aware of all accesses to
the file on which it is granting a lease. Since vfs does not
currently inform file systems about the granting and rescinding of
leases, a clustered file system cannot allow a samba server to support
OpLocks on its files and this has a negative impact on performance.
What I think is needed is to add a file systems defined
file_operations function, that would be invoked when vfs is
considering the granting of a lease on a file associated with an
inode. Such an enhancement would allow a file system to be come aware
of vfs lease activity and allow it to support this activity.
NFS has similar issues because Linux NLM-VFS does not invoke server side
filesystem specific lock method. This implies NFS client applications is
not able to use posix locks to coordinate file access across different
nodes with a cluster filesystem, even the cluster filesystem itself
does support posix locking. IBM Research and University of Michigan CITI
group have worked out a set of patches to remedy the issue:
http://www.opensubscriber.com/message/linux-fsdevel@xxxxxxxxxxxxxxx/5527833.html
-- Wendy
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